The process of contacting one fluid with another fluid in counter-current flow in a contacting unit for such purposes as absorption, reaction, and stripping is well known in the art. Fluid, as used herein, is defined as any mass of solid particles, liquid or gaseous material capable of fluidic motion. Generally, such fluid to fluid contacting units are designed with an inlet at one end of a vessel to receive a first fluid to be contacted with another fluid and an inlet at the other end of the vessel to receive the other fluid. The desire in such a unit is to maximize the contacting efficiency between the two fluids. However, problems with channeling of one of the contacting fluids in the vessel and other causes of insufficient mixing often reduce contacting efficiency.
A specific example of this is in the contacting of finely divided spent catalyst from a fluidized bed in a fluidized bed catalytic cracking unit (commonly referred to as FCCU) with stripping gas for the removal of hydrocarbon reaction products from the spent catalyst. The finely divided spent catalyst is directed downwardly in the stripping zone and the stripping gas, typically steam, is directed upwardly in the stripping zone. Many efforts have been made to improve the spent catalyst/steam contacting efficiency. See, for example, U.S. Pat. No. 5,015,363 (Cetinkaya); U.S. Pat. No. 5,141,625 (Lomas); U.S. Pat. No. 4,364,905 (Fahrig et al.); U.S. Pat. No. 4,500,423 (Krug et al.); U.S. Pat. No. 5,316,662 (Cetinkaya). These efforts are indicative of the great need in the industry for improved fluid to fluid contacting. Thus, it is desirable to have a method and apparatus for contacting one fluid with another fluid, and more particularly, spent FCCU catalyst with stripping gas, in a more efficient manner.